Hole-finishing method and apparatus



0a. 8,1929. B. A. EVANS 1,730,650

HOLE FINISHING METHODAND APPARATUS Filed June 1, 1927 2 Sheets-Sheet l I o s,1929.

EyANs ROLE FIYISHING METHOD AND APEARATUS Filed J une 1, 1927 2 Sheets- Sheet 2 Patented Oct. 8, 1929 UNITED STATES PATENT OFFICE BENJAMIN A. EVANS, OF CUYAHOGA FALLS, OHIO, ASSIGNOR TO THE B. F. GOODRIOH COMPANY, on NEW YORK, N. Y.,

A CORPORATION OF NEVJ' YORK HOLE-FINISHING METHOD AND APPARATUS Application filed June 1,

This invention relates to methods and apparatus for finishing holes formed in articles of hard material such as hard rubber covers for storage batteries. In the molding of such pieces the holes for the electrodes and filler plugs are formed by suitable molding cores, but the construction of the mold is commonly such as to leave more or less of an unavoidable fin or flash projecting across the hole in the molded article. It has been the usual practice heretofore to remove these fins with a hand tool such as a knife, but that is a rather slow operation and it is difficult therewith to obtain that degree of accuracy as to size and finish which is desirable in the completed article.

My invention has forits object to provide a method, and a suitable automatic apparatus for carrying out such method, whereby a hole-finishing operation of the nature referred to or any similar nature may be rapidly and accurately performed with a minimum of expenditure of time and labor.

Of the accompanying drawings, Fig. 1 is a side elevation of a hole-finishing machine constructed in accordance with and adapted for the performance of my invention, a portion. of one of the work-rests being broken away.

Fig. 2 is a front elevation of said machine.

Fig. 3 is a section on a larger scale, taken through the abrading tools on the line 33 of Fig. 2.

Fig. 4 is a plan View showing a battery cover having holes of a form and spacing adapted to be finished by the operation'of the machine as shown in the preceding views.

In the drawings, Fig. 4, is a battery jar cover adapted to be molded of hard rubber or equivalent composition and formed with two round holes 11, 11 for the reception of the battery electrodes, and a filler-cap hole 12 be tween the electrode holes, said hole 12 in this instance having inwardly-projecting flanges 13 on opposite sides for locking the filler or vent cap with a quick-acting joint of the breech-block type.

As the fin or flash resulting from the molding operation often forms a more or less complete septum across the hole, it is desirable to 1927. Serial No. 195,657.

punch out this fin as the initial step in thefinishing operation and immediately to follow this with an abrading action against the hole edges, which can best be performed by means of abrasive broaching tools shown in Figs. 1, 2 and 3, to which the machine imparts a rapid reciprocating motion of comparatively small amplitude.

14, 14 are the two abrasive tools for finishing the round electrode holes, and 15 is the abrasive tool for finishing the central or fillercap hole, the latter tool having a contour conforming to the shape of said hole 12, as will be apparent. The tools may be of any suit-- able abrasive material or composition, such as carborundum. These three tools are fixed upon respective rods or plungers 16, 16 and 17, and the ends of said rods below the tools are formed with conical points 18, 18 and 19 for performing the initial breaking or punching out of the fins or flash.

At the ends of this group of' tools are mounted a pair of horizontal bars 20, 20 adapted to form an upper rest against which the operator may hold the work to steady it and secure its proper alignment with the tools during the finishing operation or the latter part thereof. Each of these bars forms part of an L-shaped piece whose vertical member 21 is secured to a portion 22 of the machine frame and made adjustable for height thereon by suitable bolts 23 occupying slots in said member 21. I

The tool-rods or plungers 16, 17 are extended upwardly through guides 24, 25 on a frame member 26 and are surrounded by springs 27 whose lower ends rest upon or adjacent to the lower guide 24 while their upper ends abut against collars 28 fixed upon the several rods whereby upward retracting movement is imparted to the rods. The downward projecting movement is imparted by a series of three eccentric cams 29 formed upon a horizontal shaft 30 which is mounted in suitable'bearings on the machine, said cams working against the heads of respective tappets 81 acting upon and in line with the upper ends of the rods 16, 17.

The shaft 30 has a pulley 32 on one end conon the shaft of an electric motor 35 mounted at the top of the machine.

In the operation of my invention the abrasive tools 1d, 15, together with the pointed punches 18, 19 below them, are reciprocated at a rapid rate by the action of the cams 29 on the shaft 30. A rate of 1725 reciprocations per minute has actually been used, and while this might be varied more or less, the rate should be sufficiently rapid that there is but little tendency to communicate the motion of the tools to the work, and the amplitude of said motion is also comparatively short, so that the distance through which the tools exert their friction upon the work in connection with the rapidity of their motion has but little tendency to overcome the inertia of the work and of the operators hand moving or holding said work upwardly against the work rests 20.

It will be noted furthermore that the middle cam 22, which operates the tool 15, is opposite to the two end cams 29 which operate the tools 14, so that the drag of the middle tool is opposed to that of the two end tools, and this arrangement further tends to avoid communicating motion of the tools to the work. 7

The work held in the operators hand is brought gradually upward against the reciprocating tools and the descending points 18, 19 first break through the fins or flash across the bottoms of the holes 11 and 12, and a fur ther upward movement causes the abrasive tools 14, 15 to grind or broach away the eX- cess material and impart the desired accurate finish to the edges of the holes, the diameters of the tools being approximately equal to the molded diameters of the holes, the work 10 being finally brought up against the work-rests 20 as indicated by the broken lines in Fig. 2, and then withdrawn. 7

It is contemplated that various changes in the foregoing embodiment may be made within the scope of the appended claims.

I claim:

1. The method of finishing a series of holes in an article which comprises abrasively breaching concurrently the edges of said holes with a rapid reciprocating action the direction of which at a given instant is oppo site in different holes, whereby frictional drag on the article is substantially equalized to permit manual manipulation thereof.

2. The method of clearing and finishing the edge of a hole in a hardened plastic article which comprises punching out the mold ing fin from the h ole by a rapid reciprocatory rectilinear movement of a suitable punching and finishing instrumentality, and, concurrently abrasively trimming the edges of the hole.

3. An apparatus for finishing holes comtilinear motion for simultaneously operating upon the edges of a plurality of holes in the work, and means for rapidly reciprocating prising an aligned group of three abrasive tools mounted for parallel, rectilinear motion, and means for imparting rapid reciprocation to said tools, the middle tool having its abrasive surface of irregular shape and of greater cross sectional area than that of the other tools, the movement of the middle tool at a given instant being opposite in direction to that of the two end tools in the group.

5. In an apparatus for finishing holes, the combination of a tool assembly consisting of an abrasive tool and a pointed punch immediately beyond said tool whereby said assembly may act first to punch out a transverse fin from a hole in the work and then finish the edges of said hole, and means for imparting rapid reciprocating movements to said tool assembly.

6. In a machine for finishing holes, the combination of an aligned group of three tool assemblies, each comprising an abrasive edge-finishing tool and a pointed punching tool located immediately beyond said abrasive tool, and means for imparting rapid, rectilinear, reciprocating movement to said tool assemblies, the movement of the middle tool assembly being opposite in direction to that of the two end assemblies.

7. The method of finishing a hole in brittle material which comprises abrading the edge of the material defining the hole by a reciprocatory movement of an abrading surface, the rate of such. reciprocatory movement being suificiently great and the amplitude of the rec-iprocations being sufficiently small that the material can be held manually in alignment with the abrading tool during such abrading action. 7

In witness whereof I have hereunto set my hand this 19th day of May, 1927.

BENJAMIN A. EVANS.

prising a plurality of abrasive broaching tools mounted for parallel non-rotary, tree 

